In passenger aircrafts of older design, if the air-conditioning system fails completely, the pilot has to lower the flying altitude from, for example, 30,000 feet to 10,000 feet on long-haul flights, and open a window in the aircraft's cockpit, in order thus to supply the passengers in the cabin with fresh air. Aircraft of more recent design have a so-called emergency ram air inlet (ERAI), consisting of a valve in the wing box under the aircraft fuselage. In aircrafts with an ERAI valve, in such an emergency situation the pilot can actuate a push-button in the cockpit, whereupon the ERAI valve in the aircraft fuselage opens and fresh air can flow into the passenger cabin. In order to be able to supply the passengers with sufficient fresh air when the aircraft is fully occupied, the size of the valve and the opening angle of the ERAI valve are configured accordingly. The ERAI valve is fully opened in an emergency situation and otherwise kept closed.
FIG. 1 shows the prior art with the ERAI valve 1 actuated by a push-button 12, for example. Accordingly, the valve is either “fully closed (1′)” or “fully open (1″)”.
On long-haul flights, for example over the polar regions, at a flying altitude of 10,000 feet, the outside air temperature can easily be as low as minus 38° C. If the pilot has to change the flying altitude to this altitude owing to complete failure of the air-conditioning system, and if a conventional ERAI valve is used, the cabin temperature may drop to 0° C. or lower, which may present a serious danger to the health for at least some of the passengers, as the flight at an altitude of 10,000 feet may possibly last several hours. It should also be assumed that in such an emergency situation, passengers do not have access to appropriately warm clothing or the supply of blankets to passengers is inadequate. Owing to the consequences to health then to be expected or the refunds claimed by the passengers concerned, an airline would have to reckon on considerable financial claims, which again should be avoided. The object of the present invention is therefore to provide an improved ERAI valve of the previously mentioned type, with which the aforementioned problem no longer occurs.